A very important mineral from which titanium compounds and especially titanium dioxide for use as a pigment are extracted is ilmenite which has the theoretical formula FeO.TiO.sub.2. However, naturally occurring ilmenite ores contain ferric iron in addition to ferrous iron.
Consequently, a conventional process for the extraction of titanium oxide from an ilmenite ore comprises digestion of the ore with sulphuric acid to form a titanium sulphate solution which also contains iron sulphates followed by reduction of this solution to ensure that all the iron present is in the ferrous state. Generally, a proportion of the titanium is reduced to the trivalent state during this step. The reduction is necessary to ensure that a minimum amount of hydrous iron oxide is precipitated when the sulphate solution is hydrolysed to form hydrous titanium oxide and a conventional method for carrying out the reduction is to add scrap metallic iron. Disadvantageously, the addition of scrap iron leads to an increased quantity of ferrous sulphate which must necessarily be processed or disposed of in an environmetally acceptable manner.